Loans Held for Investment portfolio and Related Allowance for Loan and Lease Losses (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Individually evaluated	$ 3,162			$ 3,078
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	374			364
Collectively evaluated	118,530			118,013
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,751			1,810
Total evaluated	121,692			121,091
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	2,125			2,174
Loans Receivable, Fair Value Disclosure	339	[1]		379	[1]
Total	122,031	[1]		121,470	[1]
Loans and Leases Receivable, Allowance	2,125		2,152	2,174		2,300	2,348	2,457
Commercial Portfolio Segment [Member]
Individually evaluated	208			138
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	18			7
Collectively evaluated	59,837			58,750
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	901			895
Total evaluated	60,045			58,888
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	919			902
Loans Receivable, Fair Value Disclosure	0			0
Total	60,045			58,888
Loans and Leases Receivable, Allowance	919		921	902		887	901	964
Residential Portfolio Segment [Member]
Individually evaluated	2,851			2,859
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	347			348
Collectively evaluated	39,090			39,961
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	699			783
Total evaluated	41,941			42,820
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	1,046			1,131
Loans Receivable, Fair Value Disclosure	339			379
Total	42,280			43,199
Loans and Leases Receivable, Allowance	1,046		1,087	1,131		1,277	1,315	1,354
Consumer Portfolio Segment [Member]
Individually evaluated	103			81
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	9			9
Collectively evaluated	19,603			19,302
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	151			132
Total evaluated	19,706			19,383
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	160			141
Loans Receivable, Fair Value Disclosure	0			0
Total	19,706			19,383
Loans and Leases Receivable, Allowance	$ 160		$ 144	$ 141		$ 136	$ 132	$ 139

[1] 2 Includes loans of consolidated VIEs345 365